diff --git a/pylsp/python_lsp.py b/pylsp/python_lsp.py
index 3eeb2f7f..e2b541d5 100644
--- a/pylsp/python_lsp.py
+++ b/pylsp/python_lsp.py
@@ -295,7 +295,7 @@ def capabilities(self):
                 "openClose": True,
             },
             "notebookDocumentSync": {
-                "notebookSelector": {"cells": [{"language": "python"}]}
+                "notebookSelector": [{"cells": [{"language": "python"}]}]
             },
             "workspace": {
                 "workspaceFolders": {"supported": True, "changeNotifications": True}
diff --git a/test/test_notebook_document.py b/test/test_notebook_document.py
index e8e7ac75..6050b58f 100644
--- a/test/test_notebook_document.py
+++ b/test/test_notebook_document.py
@@ -33,7 +33,8 @@ def test_initialize(client_server_pair):
         },
     ).result(timeout=CALL_TIMEOUT_IN_SECONDS)
     assert server.workspace is not None
-    assert "notebookDocumentSync" in response["capabilities"].keys()
+    selector = response["capabilities"]["notebookDocumentSync"]["notebookSelector"]
+    assert isinstance(selector, list)
 
 
 @pytest.mark.skipif(IS_WIN, reason="Flaky on Windows")